The overall goal of this project is to investigate the early postnatal development of the basal ganglia system in non-human primates. The main emphasis will be placed on the changes in neuronal organization and in the amount and localization of certain putative neurotransmitters over the first 16 weeks of postnatal life. The specific structures to be studied in the period covered by this proposal will be the neostriatum and pallidum, and the synaptically active substances will be serotonin, substance P and the enkephalins. These goals will be accomplished at the light (LM) and electron microscopic (EM) levels with a wide range of procedures, from the classic Nisal and Golgi methods for LM to immunocytochemistry of serial sections for EM, and with the application of both qualitative and quantitative techniques. Our studies are designed to obtain primarily normative data as a first step to investigate possible alterations produced by interference with normal perinatal development due to traumatic, metabolic or environmental factors. The studies on neuronal organization of each structure will address themselves to four basic questions: (1) What is the synaptic endowment at birth; (2) What are the changes in synaptic organization occurring during the first 16 weeks of life; (3) Is there cell death during this period; (4) Is there a remodelling process preceding the stabilization of the mature synaptic pattern. The investigations on the putative neurotransmitters will answer the question of: (1) localization, amount and distribution in the neuronal circuitry of elements containing them; (2) changes in these properties over time. The scientific disciplines involved in this project are Neuroanatomy and Developmental Neurobiology. The health related implications of the research is to provide the morphologic bases for the understanding of mechanisms involved in disease of the basal ganglia such as Parkinson's Disease and Huntington's chorea, and disorders of motor functions due to perinatal pathologic processes.